The continuing advance in data processing systems has been accompanied by the need for terminal display and recording systems which make optimum use of a data processor's data handling capabilities. Typical video read-out facilities involve the use of a cathode ray tube display, wherein image signal processing results in a pictorial display on the face of the CRT. In addition to such a primary recording medium, secondary storage apparatus, such as video copying devices, may be used in conjunction with the display on the CRT, so that the image electronically projected on the CRT screen may be retained on a secondary storage medium.
One such system for so recording electronicaly processed and video stored data is described in U.S. Pat. No. 3,457,371 to A. U. Sharon. The graphic display system described therein employs a CRT for graphically displaying computer-processed information, such as a two-dimensional data plot. Optically coupled to the CRT screen, and external to the tube, is a xerographic recording apparatus, by way of which information from the data processing system displayed on the CRT during real time is recorded on a xerographic plate by a PROXI (projection by reflection optics of xerographic images) process. The image retained on the xerographic plate may be viewed by an optical system separate from that permitting direct viewing of an image on the face of the CRT. A further display may be initiated and its image retained by erasing the xerographic plate and subsequently recording the new CRT image on the plate.
Although an auxiliary image storage system of the type described in the patent to Sharon permits retention of a video processed image on a medium other than the CRT screen, the field of view is limited and multiple projection and recordation is not provided. Furthermore, the relatively low light intensity available from the screen of a cathode ray tube is not sufficient to permit satisfactory large scale image projection, particularly under normal ambient lighting conditions.
A specialized cathode ray tube storage and transfer system of the type wherein electronically processed information may be recorded on a magnetic tape by way of the CRT is described in the U.S. Pat. No. 3,689,934 to Nacci. The cathode ray tube has a particular thermomagnetic sensitive structure so that a thermomagnetic image is created on the face plate, with the selective magnetizations then being used to transfer the image to a magnetic tape, a line at a time. While the system described in this patent derives a magnetically transferrable image from a modulated cathode ray, the pattern stored on the tube is limited, not widely and multiply displayed, and information is transferred by a line-at-a-time magnetic tape mechanism which must be positioned immediately adjacent the face of the tube, preventing direct display of the recorded pattern.
Projection of the information pattern created on the surface of a deformographic type storage tube is described in U.S. Pat. No. 3,385,927 to Hamann and U.S. Pat. No. 3,902,012 to Dalton et al. However, the singular type of display described therein is akin to the basic CRT display provided by the system described in the Sharon patent. Multiple and separate imaging and/or recording of the deformographically stored pattern are not provided.